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A novel crosslinking protocol stabilizes amyloid ? oligomers capable of inducing Alzheimer's-associated pathologies.

ABSTRACT: Amyloid ? oligomers (A?Os) accumulate early in Alzheimer's disease (AD) and experimentally cause memory dysfunction and the major pathologies associated with AD, for example, tau abnormalities, synapse loss, oxidative damage, and cognitive dysfunction. In order to develop the most effective A?O-targeting diagnostics and therapeutics, the A?O structures contributing to AD-associated toxicity must be elucidated. Here, we investigate the structural properties and pathogenic relevance of A?Os stabilized by the bifunctional crosslinker 1,5-difluoro-2,4-dinitrobenzene (DFDNB). We find that DFDNB stabilizes synthetic A? in a soluble oligomeric conformation. With DFDNB, solutions of A? that would otherwise convert to large aggregates instead yield solutions of stable A?Os, predominantly in the 50-300 kDa range, that are maintained for at least 12 days at 37°C. Structures were determined by biochemical and native top-down mass spectrometry analyses. Assayed in neuronal cultures and i.c.v.-injected mice, the DFDNB-stabilized A?Os were found to induce tau hyperphosphorylation, inhibit choline acetyltransferase, and provoke neuroinflammation. Most interestingly, DFDNB crosslinking was found to stabilize an A?O conformation particularly potent in inducing memory dysfunction in mice. Taken together, these data support the utility of DFDNB crosslinking as a tool for stabilizing pathogenic A?Os in structure-function studies.

SUBMITTER: Cline EN

PROVIDER: S-EPMC6424489 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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A novel crosslinking protocol stabilizes amyloid β oligomers capable of inducing Alzheimer's-associated pathologies.

Cline Erika N EN Das Arighno A Bicca Maíra Assunção MA Mohammad Saad N SN Schachner Luis F LF Kamel Josette M JM DiNunno Nadia N Weng Anthea A Paschall Jacob D JD Bu Riana Lo RL Khan Faraz M FM Rollins Madeline G MG Ives Ashley N AN Shekhawat Gajendra G Nunes-Tavares Nilson N de Mello Fernando G FG Compton Philip D PD Kelleher Neil L NL Klein William L WL

Journal of neurochemistry 20190129 6

Amyloid β oligomers (AβOs) accumulate early in Alzheimer's disease (AD) and experimentally cause memory dysfunction and the major pathologies associated with AD, for example, tau abnormalities, synapse loss, oxidative damage, and cognitive dysfunction. In order to develop the most effective AβO-targeting diagnostics and therapeutics, the AβO structures contributing to AD-associated toxicity must be elucidated. Here, we investigate the structural properties and pathogenic relevance of AβOs stabil ...[more]

PMID: 30565253

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Project description:Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the pathological aggregation of the amyloid-? peptide (A?). Monomeric soluble A? can switch from helicoidal to ?-sheet conformation, promoting its assembly into oligomers and subsequently to amyloid fibrils. Oligomers are highly toxic to neurons and have been reported to induce synaptic transmission impairments. The progression from oligomers to fibrils forming senile plaques is currently considered a protective mechanism to avoid the presence of the highly toxic oligomers. Protein nitration is a frequent post-translational modification under AD nitrative stress conditions. A? can be nitrated at tyrosine 10 (Y10) by peroxynitrite. Based on our analysis of ThT binding, Western blot and electron and atomic force microscopy, we report that A? nitration stabilizes soluble, highly toxic oligomers and impairs the formation of fibrils. We propose a mechanism by which fibril elongation is interrupted upon Y10 nitration: Nitration disrupts fibril-forming folds by preventing H14-mediated bridging, as shown with an A? analog containing a single residue (H to E) replacement that mimics the behavior of nitrated A? related to fibril formation and neuronal toxicity. The pathophysiological role of our findings in AD was highlighted by the study of these nitrated oligomers on mouse hippocampal neurons, where an increased NMDAR-dependent toxicity of nitrated A? oligomers was observed. Our results show that A? nitrotyrosination is a post-translational modification that increases A? synaptotoxicity. SIGNIFICANCE STATEMENT:We report that nitration (i.e., the irreversible addition of a nitro group) of the Alzheimer-related peptide amyloid-? (A?) favors the stabilization of highly toxic oligomers and inhibits the formation of A? fibrils. The nitrated A? oligomers are more toxic to neurons due to increased cytosolic calcium levels throughout their action on NMDA receptors. Sustained elevated calcium levels trigger excitotoxicity, a characteristic event in Alzheimer's disease.

Dataset Information

A novel crosslinking protocol stabilizes amyloid ? oligomers capable of inducing Alzheimer's-associated pathologies.

Publications

A novel crosslinking protocol stabilizes amyloid β oligomers capable of inducing Alzheimer's-associated pathologies.

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